1. Field of the Invention
This invention lies in the field of gaseous and liquid fuels burning systems. More particularly, it concerns the design of a burning system which can use either, or both, liquid fuel and gaseous fuel.
More particularly, it is concerned with a type of burner system in which the production of NOx is minimized.
One of the undesirable products formed as fuel burns is typically nitric oxide (NO) which readily reoxidizes to nitrogen oxide (NO.sub.2). Because of the number of oxides of nitrogen that may form, they are commonly referred to as NOx. NOx, in the air, is a serious pollutant, which is the subject for EPA regulation, as to maximum emission to the atmosphere, in any case of venting of products of combustion to the atmosphere, as from a typical chimney or stack.
NOx emission is measured in parts per million (PPM) in stack gases, and some fuels, as they burn, are capable of generation of several hundred PPM. New EPA regulations, as proposed, will limit tolerable NOx emission to not more than one hundred PPM. Means for reduction of emitted NOx are demanded for fuel burning as fuel is typically burned.
2. Description of the Prior Art
In the prior art, the means for reduction of emitted NOx in the products of combustion of a furnace or stack, involves generally the cumbersomely and expensively recirculated flue gases from the stack or chimney, back into the combustion zone. This involves motor-driven fans and ducts to accomplish the recirculation of the high temperature combustion products to the combustion zone, of one or more burners.
A more recent development is illustrated by the U.S. Pat. No. 4,004,875, which utilizes the recirculation of products of combustion without, however, using the expensive construction of blowers and ducts, etc. However, none of the prior art systems utilize the simple feature of the present invention.